Black holes are some of the most mysterious objects in the universe — what is left behind after a star has collapsed. NASA has compiled several dramatic images of what are believed to be black holes in space.
NGC 474 is an elliptical galaxy in the constellation Pisces. This large galaxy is known to possess tidal tails, although their origins remain unknown. These tidal tails may be related to debris left over from absorbing numerous small galaxies in the past.
Exploring Universe: Thomas Wright presents an alternate view of the Milky Way galaxy in cross section. Plates XXXI and XXXII show the universe filled with many systems like our own, each a star-filled shell surrounding its own "eye of Providence" - from A